The halting attempt by the US and Mexico to find the body of David Hartley and establish security on the deceptively placid lake highlights the degree to which cross-border communications and trust have broken down since the start of the Mexico drug war in 2006, says Texas state legislator Aaron Pena.

The result is that an issue that once might have been handled between local officials from Texas and the Mexican border state of Tamaulipas has now escalated into an international incident demanding the involvement of the Obama administration.

That is often no longer the case, mostly because Mexican officials who had good relations with local government and law enforcement in Texas have been forced to flee from the drug war that has claimed more than 26,000 Mexicans in the past four years, says Mr. Pena, the Texas lawmaker.

"The leaders of border communities on the Mexican side now live on our side," says Pena, who met with local and state law-enforcement officials at the lake on Wednesday. "Plus the cartels have infiltrated many aspects of government on the border, they've infiltrated law enforcement, so you don't know who to trust anymore."

The incident began last Thursday afternoon when presumed Mexican pirates, already implicated earlier this year for robbing US bass boaters who had crossed over to the Mexican side, began shooting at Mr. Hartley and his wife, Tiffany, who had gone six miles into Mexico to visit the ruins of a submerged church.

Ms. Hartley says that when her husband was shot, she doubled back to try to fetch him, but had to abandon the rescue effort in order to escape. One eyewitness saw a boat matching Ms. Hartley's description of the boat used in the alleged attack chasing her deep into US waters. A memorial service for Mr. Hartley was held Tuesday.

Mexico: No formal complaint

Amid pleas from the family and wife of Mr. Hartley, the US has put pressure on Mexican authorities, some of whom have publicly doubted the veracity of Ms. Hartley's story. Mr. Hartley's father, Dennis Hartley, told the Associated Press, "I don't think at this time ... Mexico is really doing anything."

Tamaulipas state police, however, say that Ms. Hartley must file a formal complaint before they can begin an official investigation. Ms Hartley is expected to travel to Mexico today. In the meantime, an informal search has already been launched, said Ruben Dario Rios, a spokesman for the state attorney general's office, according to published reports.

US officials and politicians like Sen. John Cornyn (R) of Texas and Rep. Henry Cuellar (D) of Texas say they've been in communication with various Mexican agencies since the shooting happened and demand prompt action.

"David Hartley must be found," Congressman Cuellar told a Texas newspaper. "We can and must continue to urge our Mexican counterparts to search for David Hartley.”

On Wednesday, that pressure seemed to pay off as Mexican officials began a more thorough search, using helicopters and more boats on the Mexican side of Falcon Lake, which US authorities are not allowed to patrol. The investigation also appears to be making some headway as Texas authorities glean more information from sources on the other side of the lake.

Yet the cross-border tension remains palpable as Zapata County Sheriff Sigifredo Gonzalez, who is heading up the investigation on the US side, declined an invitation to join the search in Mexico. "I think if we go out there and we end up getting into a gun battle, it's definitely an international incident that would have some repercussions," he said.

'Take back the lake'

In an interview on KURV radio in Texas, Ms. Hartley herself echoed a call by Texas Gov. Rick Perry to address the situation not just diplomatically, but with a show of force, including more National Guard troops.

“They need to have a realization, a wake-up call," Ms. Hartley said. "We need to get people down here. We need to get our Army and military and whoever. We need to double our Border Patrol and take back the lake. Why in the heck do [the cartels] have [control of] that lake? They have most of that lake.”

Pena echoed her sentiments: "On the Mexican side every inch is controlled by the cartels and it's a hotbed of criminal activity."

In the past, the Obama administration has defended its border policy against critics, saying it has spent more time and money, and deployed more National Guard troops to secure the border than any other administration. Department of Homeland Security spokesman Matt Chandler said the US government has offered resources to help find Mr. Hartley.

Nevertheless, pressure is rising on the Obama administration to get more directly involved with the situation on Falcon Lake.

"President Obama says he wants lawmakers in both houses of Congress to make progress this year on reforming the immigration system," writes Jim Kouri, vice president of the National Association of Chiefs of Police, on the Borderfire Report blog. "However, he's not talking about how his administration is failing to protect citizens from criminal aliens."